FIG. 1 shows a side-view of an eye 10. Eye 10 includes a cornea 11, an iris 12, a pupil 14, a lens 15, and a retina 16. Light enters the eye through pupil 14, is focused and inverted by cornea 11 and lens 15, and is projected onto retina 16 at the back of the eye. Iris 12 acts as a shutter that can be opened or closed to regulate the amount of light entering the eye via pupil 14.
Retina 16 is a seven-layered structure that converts received light into a neural signal. This conversion process is known in the art as “signal transduction”. The actual photoreceptors on the retina are rods and cones, but the cells that transmit the resulting neural signal to the brain are ganglion cells. The axons of these ganglion cells make up the optic nerve 17.
Retinal imaging systems operate by directing light into a patient's eye to illuminate a portion of the retina. A camera captures an image of the illuminated portion of the retina via light reflected off of the retina. Obtaining a clear retinal image has proven difficult in the past due, at least in part, to mingling of light used for illumination with light used for imaging and, in part, due to the reflections off of the cornea. For example, traditional retinal imaging systems use inner and outer paths (e.g., concentric paths) for imaging and illumination, respectively. In these systems, light from the illumination path often mingled with light for imaging, resulting in poor quality images.